Japanese Basics: Kaeshi, soba and udon noodle soup or sauce base

When the weather gets warmer, we eat a lot of cold Japanese noodles: soba (buckwheat noodles), hiyamugi (thin wheat noodles), so-men (even thinner wheat noodles), Sanuki udon (thick wheat noodles- Sanuki is the name of a region famous for udon) and harusame (bean or ‘glass’ noodles). For most cold noodle dishes a salty sweet soy sauce based soup or dipping sauce called mentsuyu is used. You can buy pre-made mentsuyu concentrate, but to me most of them taste too sweet or are overwhelmed by a too-strong MSG or similar artificial tasting umami flavor. Making mentsuyu at home from scratch is not so difficult, and the difference in taste is quite worth the little extra effort.

The base of mentsuyu is a mixture of soy sauce, sugar and mirin called kaeshi (or hon-gaeshi: hon means “real” or “authentic”). It can also be used as a flavoring base for many other things. You just need good quality dark soy sauce, white sugar, and good quality mirin. It keeps for months in the refrigerator, or even in the freezer (where it will stay liquid) so I like to make as big a batch as I can afford to price-wise and fridge-space-wise.

This is similar to the Japanese essence mix, but doesn’t include the kombu seaweed or bonito. If you are a vegetarian you can use kaeshi safe in the knowledge that it’s totally vegan, and combine it with a vegetarian stock. Kaeshi also lasts a lot longer since the basic ingredients are indefinite keepers.

I’ll be talking about cold noodles and such in upcoming posts, so if you’d like to follow along, you may want to make some kaeshi to be ready.

Put the mirin in a pan and bring up to the boil; lower the heat and let simmer a bit to evaporate much of the alcohol content.

Add sugar and stir until melted. Add the soy sauce, and let it warm up slowly, stirring. It should never boil - once it starts barely bubbling, take it off the heat.

If any cloudy scum has accumulated on the top, skim off carefully. I t can be used right away, but is best when allowed to rest for at least a day.

Let cool and store in a glass or other non-reactive, airtight container in the refrigerator. (I keep it in preserving jars with screwtop lids.) It will keep for several months under refrigeration.

Notes

I like this to be not that sweet, but I am from the Kanto (Tokyo) area. People from the Kansai area would use 1 cup of sugar for this instead of 3/4ths. You may want to adjust the amount of sugar to your taste.

In Japan, use san-on-to- (三温糖) or cooking sugar.

If you are sugar-intolerant in any way, a heat-safe sugar substitute should work, though it’s not tested here.

Mirin is a fortified sake with alcohol content, and is primarily used as in cooking rather than for drinking. Honmirin (本みりん）is ‘real’ mirin, made with traditional methods. You may also see aji mirin or mirin choumiryou for sale - this is an alcohol-free (or very low alcohol) mirin flavoring, a fairly modern invention. I prefer hon mirin since I think it has a better flavor (also, better brands of mirin only come as hon mirin)

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Thank you so much for posting this recipe! I’ve been wanting to make some cold soba or somen now that it’s about 100F/38C here in Arizona and I don’t really care for the premade bottled mentsuyu out there. My grandpa used to make cold o-somen for us when we’d go visit but I never found out what he used to make his. Anyway, horray for cold noodles!

Most of the soy sauce you’ll see sold generally is dark soy sauce. Light soy (usukuchi) is generally only available in Japanese food stores (it’s lighter in color, but actually higher in salt content). So regular Kikkoman is fine.

Whoa, this is a very old comment but I don't think I answered it. To clear up any confusion, the "hon" prefix means "real" or "authentic". Therefore, hon-mirin does not mean bottle of mirin. It means "real" mirin, as opposed to say, "aji-mirin" which indicates it's a processed mirin flavored flavoring ingredient.

Can I use Chinese dark soy sauce? Is it the same as Jap dark soy sauce? If it is not advisable to use Chinese dark soy sauce, can you recommend a few Japanese brands of dark soy sauce that taste good? We have Japanese supermarket (Isetan) here.

Japanese and Chinese soy sauce is made from different ingredients. I prefer the taste of low sodium Yamasa but it is hard to find. Kikoman is found all over the world but the low sodium version is harder to find.

Wow…and here I thought it was always made with komb, bonito, and those big dried fishies…..saw my mom making it when I was growing up, and always followed the same thing…..its about the only thing I attempt to make without measuring ingredients.

jani, basic kaeshi doesn’t have the dashi ingredients you mention in it…I think because that would lessen the keeping qualties. I do have a version which has dashi ingredients (see here) but it has to be refrigerated. That’s probably closer to what your mother made.

I made this recipe for zaru soba with great success. Now I have a lot left over! You mentioned that is can be used as a flavoring base for many other things, and I was wondering if you could add some links to other recipes or uses for Kaeshi. Thanks for making Japanese food so accessible - I love this blog.

My taste buds may be defective, but I don't particularly
like sweet things. In consequence, my kaeshi [if that's
even its proper name] is: 10 parts shoyu to 1 part mirin.
I just need a bit of sweetness to take the edge off the
saltiness of the shoyu. I wonder is this formula
unusual? In any case, it's perfect for me.

Thanks, Maki. The proportions I used were
abstracted out of a recipe for Tosa dipping
sauce, which stipulated a 10-to-1 ratio.
After experimentation, I got the ratio down
to 7-to-1. In any case, though I may sometimes
take my own path, I always appreciate your
guidance.

Thanks so much for this base. As a college student, my budget is limited and this soup base is something I can recreate and mess around with the things I have in my fridge. Might not turn out Japanese *at all*, but its something easy I can turn to when I want something that gets me excited about my leftovers (and isn't MSG-filled).

For example, I had a box of decent msg-free chicken broth, low sodium soy sauce, and some random veggies that needed to be used up (carrots, green onion). I love throwing random veggies from my fridge into an otherwise boring pasta or rice dish (which I keep around in bulk).
For the chicken broth version, I didn't have enough soy sauce (and on a freezing cold day when I didn't want to run back to the store), so I used these together with some shiitake mushrooms and it tasted quite good, although not something I would call Japanese. With just a little bit of tofu (also cheap and tasty), it kept my tummy full (and happy) all day.
Now, if only I could find a way to make okonomi yaki on the cheap....

I just bought the shoyu yesterday. Can't wait to make it! Just want to check, after I made the kaeshi, can I dilute it with dashi stock immediately to make soba tsuyu, and store it in the fridge for convenient use later? Thanks!

I am looking for a recipe that seems like it may be pretty simple. Its a vinegar sauce (clear--not sure but I dont think it has soy sauce in it) that is served with harusame (glass) noodles in a local japanese restaurant that my husband and friends often frequent. That's it--just the noodles in a light vinegar sauce --maybe some sugar in it? Have you ever heard of anything like this? I would love to make it for us because we love it so much and when we are at the restaurant--its only served as a small complementary appetizer--and we feel shy about asking for more! thanks cara

It's impossible to say unless I taste it myself, but if it's clear, salty-vinegary and a bit sweet, it's probably a sunomono sauce made with rice vinegar, salt and sugar. This page has a recipe for wakame seaweed and cucumber sunomono, which you can work off from perhaps.

Hi I tried finding mirin, I'm from Singapore but its rather tough finding, so I bought Yamasa Soumen senka soup base, can that be used as well? I'm cooking for 2 people , if I would like to try out your receipe, what would be the directions for the quanity of the sauces for me? Any form of help would be very much appreciated

I am not 100% sure since I have never used that particular product but that sounds like a readymade soup base to me. You only need to dilute it with water to use. The instructions should be on the bottle.

You can find honmirin at Meidi-ya Liang Court, but it is expensive. They carry a variety of mirin substitutes though which are labeled as "mirin seasoning" or something similar, for < $5 a bottle.

Fairprice Xtra also has mirin substitutes in the Japanese section, which are affordable and work quite well. I remember buying a bottle for just $3...

To make a cold noodle dipping sauce that tastes good, there is no substitute for using dashi made with kombu and hanakatsuo (you can buy these either at Meidi-ya or the Isetan at Shaw Centre). Sadly, I only realized this after 5 years of trying various bottled tsuyus...